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post #1 of (permalink) Old 03-21-2018 Thread Starter
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Please help with engine noise 2012 LT 3.6

2012 Impala LT 3.6 69K miles

I hope I am on the right thread and if I am not please properly direct me to the correct thread - I appreciate any help I can get.

Engine area noise that sounds like a low growling sound only when accelerating from a stop or near stop. Only happens after engine is at normal temperature. Never happens on cold engine. Never happens when the transmission is in Park or Neutral - only happens when engine is under load including reverse and low. Sounds like a low modified exhaust pipe sound but coming from the engine area. Almost sounds like a low growling rumble sound as the car is accelerating under a load like an accelerating hot rod or performance car. Also, the noise is there even when the car is still and the car is in gear with the brake on as I push down the accelerator.

Thanks for your help!

Jeff

Last edited by Jeffk426; 03-21-2018 at 11:56 AM. Reason: adding another description of noise
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post #2 of (permalink) Old 03-22-2018
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Leaky exhaust perhaps. Perfect chance to replace downpipe back exhaust. I take it this is a new noise and you've had the car for a while?
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post #3 of (permalink) Old 03-27-2018 Thread Starter
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Thanks ebt4u.

I will take a closer look at that exhaust near the engine. I had this car for 2 months now and from what I could gather the sound was
around even with the previous owner who owned it since new but not sure exactly when the sound started.

It is driving me nuts - if I didn't know better, I would almost think it was a wobbly torque converter or something like that - just a low
muffled exhaust sound when accelerating from 1 - 2 - 3 - 4 and low rpm to boot. The sound goes away at the higher range of 1 - 2 - 3 - 4 and never hear it at cruising speed with an average of 1500 - 2000 RPM'S.

The sound is not normal - that is for sure.

The car is very clean and was and is still well taken care of.

Thanks for your input.

Jeff
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post #4 of (permalink) Old 03-27-2018
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The high pressure fuel pumps on our cars can be somewhat loud too. Although I wouldn't say it sounds like a leaky exhaust. It was loud enough for me to be concerned, but then found it's normal.
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post #5 of (permalink) Old 03-27-2018 Thread Starter
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I heard that as well. I am going to have to stick my head in there and see if I can at least locate the region where this is coming from. An earlier post seemed to have this same problem and discovered it that the rear motor mount was bad and allowing some kind of vibration sound. That would make sense except my problem comes up only after the engine has thoroughly warmed up - never happens when
the engine is cold. I had thought maybe the transmission fluid was getting thinned out after warming up and causing some kind of
bearing or knocking wobble sound. I did a thorough flush and added the Lucas transmission product to no avail.

I am going to see if I can somehow record the sound and post it as well.

Thanks for your feedback !

Jeff
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post #6 of (permalink) Old 05-01-2018
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Quote:
Originally Posted by Jeffk426 View Post
I heard that as well. I am going to have to stick my head in there and see if I can at least locate the region where this is coming from. An earlier post seemed to have this same problem and discovered it that the rear motor mount was bad and allowing some kind of vibration sound. That would make sense except my problem comes up only after the engine has thoroughly warmed up - never happens when
the engine is cold. I had thought maybe the transmission fluid was getting thinned out after warming up and causing some kind of
bearing or knocking wobble sound. I did a thorough flush and added the Lucas transmission product to no avail.

I am going to see if I can somehow record the sound and post it as well.

Thanks for your feedback !

Jeff
Jeffk426: Any luck narrowing this down? My '16 LTZ Limited does the same thing. I wonder if the 9th gen 3.6s do this too.
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